Bleaching processes and compositions



United States Patent M 3,177,148 BLEACHING PROCESSES AND COMPOSITIONS Samuel Claude Bright and Francis Robert Maxwell McDonnell, Bebington, England, assignors to Lever Ilei-others Company, New York, N.Y., a corporation of No Drawing. Continuation of application Ser. No. 811,279, May 6, 1959. This application Jan. 6, 1964, Ser. No. 336,068

Claims priority, application Great Britain, May 9, 1958, 14,921/58 19 Claims. (Cl. 252-99) This invention relates to bleaching processes and compositions which are suitable for removing stains from textile materials.

This application is a continuation of Serial No. 811,- 279, filed May 6, 1959 and now abandoned.

Inorganic persalts such as sodium perborate and sodium percarbonate are widely used in detergent compositions to give them bleaching properties. These persalts provide a satisfactory bleach when the detergent composition is used at the boil, but at lower temperatures their action is rather slow. This is a considerable disadvantage in view of the wide use of washing machines which operate at temperatures of about 5060 C., for washing with detergent compositions containing persalts at these temperatures does not give a very effective bleaching action in the normal washing period. The present invention is concerned with bleaching processes and compositions in which persalts are activated so that more eflective bleaches can be obtained at these relatively low temperatures.

It has been discovered that certain acyl organo-amides have an activating efiect upon the bleaching activity of inorganic persalts at these temperatures. It is believed that the hydrogen peroxide liberated when the persalt is dissolved in water reacts with the amide to give a bleaching agent more vigorous than hydrogen peroxide, thus promoting low temperature bleaching. The ability of any particular amide to achieve this effect depends at least in part upon the electronic properties of its molecule, but it has not been found possible to define the amides which are suitable solely in terms of chemical structure, and variation of substituents in the molecule may effect profoundly the behavior of the amide in the bleaching process.

It has been found that those amides which possess the necessary properties are simply and conveniently characterized by a test in which a persalt and the amide are heated together in water and the vigorous bleaching agent thus produced is estimated by its ability to liberate iodine from potassium iodide solutions at 0 C. This test is now described.

PER-ACID FORMATION TEST A test solution is prepared by dissolving the following materials in 1000 ml. distillted water:

G. Sodium pyrophosphate Na P O .10H 0 2.5 Sodium perborate NaBO .H O .3H O (having 10.4% available oxygen) 0.615 Sodium dodecylbenzene sulfonate (the dodecyl group being that derived from tetrapropylene) 0.5

To this solution at 60 C. is added an amount of amide such that for each atom of available oxygen present one molecule of amide is introduced. A water-soluble amide 3,177,148 Patented Apr. 6, 1965 Ice or one which is liquid at 60 C. or will disperse into the solution easily is added directly to the test solution, but other amides are first dissolved in 10 ml. ethyl alcohol and then added to a test solution prepared using 990 ml. distilled water.

The mixture obtained by addition of the amide is vigorously stirred and maintained at 60 C. After 5 minutes from the addition, a m1. portion of the solution is withdrawn and immediately pipetted on to a mixture of 250 g. cracked ice and 15 ml. glacial acetic acid. Potassium iodide (0.4 g.) is then added and the liberated iodine is immediately titrated with 0.1 N sodium thiosulphate solution with starch as indicator until the first disappearance of the blue color.

An amide which is suitable as an activator for hydrogen peroxide (or persalt) in low temperature bleaching is one which in this test gives a titre of at least 1.5 m1.

Accordingly a reactive acyl organoamide as used in this specification means an acyl organoamide which has a titre of at least 1.5 ml. 0.1 N sodium thiosulphate in this test.

The processes of the invention are ones in which materials, especially soiled materials, are bleached by contacting the material with an aqueous solution of hydrogen peroxide and a reactive acyl organoamide. The compositions of the invention, which are suitable for use in these processes, comprise an inorganic persalt and a reactive acyl organoamide.

By acyl organoamide is meant an amide derived on the one hand from an organic carboxylic acid (forming an acyl radical) and on the other from an organic-substituted ammonia compound containing one hydrogen atom and at least one acyl radical attached to the nitrogen atom. The acyl organoamide is accordingly a compound of the formula RCONR R in which RC0 is a carboxylic acyl radical, R is a second acyl radical and R is any suitable radical as determined by the behavior of the corresponding compound in the Per-Acid Formation Test described above. It has been found that suitable radicals for R may generally be selected from the group consisting of alkyl, aryl, carboxylic acyl, carbamyl and sulfonic acyl radicals. Any two of the radicals RCO, R and R may be joined together in the form of a divalent radical which, with the nitrogen atom, will form a heterocyclic ring. Preferably, the radical RC0 is aliphatic, especially one containing from 2 to 4 carbon atoms, for instance the acetyl radical. Preferably also the radical RC0 is not linked with either of the radicals R and R to form a divalent radical.

The amide is preferably an acetyl organoamide, especially an acetyl organoamide in which the nitrogen of the amide group is substituted by a second acetyl radical. Other compounds which can be used are the propionyl, butylryl, and benzoyl organoamides. Many useful compounds are to be found among the arylamides, especially the anilides, for instance an NzN-diacylaniline. NzN- diacetylanilines are particularly suitable.

Examples of types of compounds in which the groups attached to the nitrogen are linked together are N-acyl lactams and N-acyl anthranils in which two acyl groups are attached to nitrogen, one being a group which is also attached to the nitrogen at a second position; this second linkage can be through a :hetero atom, as in an N-acyl saccharin: there can be three acyl groups attached to nitrogen, two of which are constituted by a single divalent radical, as in N-acyl imides of dicarboxy-lic acids.

A list of some reactive acyl organoamides is given 3 below, together with the titre which each gives in the test described above.

Tit-re N,N-diacetylaniline 6.05 NzN-diacetyl-p-toluidine 6.65 NzN-diacetyl p-cihloroaniline 5.85 NzN-dibutyrylaniline 5.2 Dibenzanilide 3.1 N-acetyl caprolactam 4.5 N:N'-diacetylbarbitone 2.8 N-acetyl phthalimide 4.35 N-acetyl saccharin 5.6

Other suitable amides are N-acetyl anthranil, and NzN- diacetyl-S:S-dimethylhydantoin. The amides concerned are normally solids and are in practice mixed with the persalt in a finely divided form in order to ensure that when the bleaching composition thus obtained is used, -it is easily dispersed in the bleaching bath. As the amides in general show a tendency to be decomposed by the persalts, the compositions should in practice be prepared just before use.

In the processes of the invention the hydrogen peroxide can be added as such directly to the bleaching bath which is to be used, but preferably it is liberated from an inorganic persalt. The inorganic persalts used in such processes or in the compositions of the invention are those which give rise to hydrogen peroxide when dissolved in water, and suitable compounds are alkali metal perborates, percarbonates, perpyrophosphates and persilicates. Such salts are believed to contain hydrogen peroxide of crystallization and may thus not be regarded as true persalts.

Preferably the bleaching compositions of the invention contain from A to 4, and especially /2 to 1 /2, molecules of reactive amide for each atom of available oxygen in the persalt used, and in the bleaching processes this ratio of amide to available oxygen is employed.

In practice the processes of the invention are carried out under alkaline conditions, especially at a pH of between 8 and 11 in order to enable the hydrogen peroxide (or persalt) to form the agent effective in low temperature bleaching. Once this has been formed the bath can be converted to acid conditions if desired. Accordingly, it is also preferable for the bleaching compositions of the invention to contain sufiicient of an alkaline substance to provide these pH conditions when the composition is used. Suitable alkaline materials are alkali metal carbonates, phosphates and silicates: the phosphates can be orthophosphates or water-soluble condensed phosphates, for instance tripolyphosphates and pyrophosphates.

Other materials can be included in the bleaching processes and compositions, and it is particularly suitable to incorporate a detergent, so that the bleaching process takes place simultaneously with a washing process. Organic detergents which can be incorporated in the bleaching bath or composition are either soaps or soapless detergents, for instance an alkylary-l sulphonate or an alkyl sulphate. Detergent bleaching compositions will in practice also contain conventional detergent adjuncts, for example alkali metal sulphates, alkaline substances such as those mentioned above, sodium carboxymethyl cellulose and fluorescent brightening agents. Generally a detergent bleaching composition will contain from to 50% by weight of organic detergent.

Materials which can be bleached by the process of the invention are those which can be bleached with persalts, for instance stained cotton fabrics and other stained or soiled fabrics and fibres.

The invention is illustrated by the following examples.

Example 1 A detergent bleaching composition was prepared using that described in Example 1.

Anhydrous alkaline sodium silicate 6.6 Tetrasodium pyrophosphate 13.1 Pentasodium tripolyphosphate 21.9 Anhydrous sodium sulphate 24.4 Water 1,2,1

To 10 parts by Weight of this detergent powder base was added 0.865 parts of sodium perborate tetrahydrate (containing 10.4% available oxygen) and 1.03 parts of NzN-diacetyl-p-toluidine.

A 0.44% by weight aqueous solution of the total composition (containing 0.37% of the detergent powder base, 0.00335% of available oxygen and 0.0382% of NzN-d-iacetyl-p-toluidine: that is 1.07 atoms of available oxygen for each molecule of the amide) was maintained in a thermostat at 60 C. A tea stained White cloth was immersed in the solution for 10 minutes and continuously stirred (the ratio of washing liquid to cloth being 20 parts to 1 by weight) after which it was taken out and rinsed in warm distilled water, and the cloth was finally dried and ironed.

The increase in percent reflectance of the cloth achieved by washing was measured with a Hunter reflectometer, using a blue filter; the increase in percent reflectance was 16.1. When a similarly stained cloth was washed in the same way with a solution of the same composition except that no amide was used an increase in percent reflectance of 10.9 was observed, indicating that the amide conferred better bleaching properties at 60 C.

Example 2 A detergent bleaching composition was prepared as in Example 1 except that N:N-diacetyl-p-chloroaniline (1.14 parts) was used as amide.

A 0.44% by weight aqueous solution of the total composition (containing 0.37% of the detergent powder base, 0.00335% of available oxygen and 0.0423% of NzN- diacetyl-p-chloroaniline: that is, 1.06 atoms of available oxygen for each molecule of the amide) was used to Wash tea stained white cloth in exactly the same way as The introduction of the amide in this instance led to an increase in percent reflectance of 17.

N:N-diacetyl-p-chloroanilin'e, M.P. 65-67.5 C., can be prepared by refluxing p-chloroaniline for several hours with acetic anhydride in the presence of a small amount of sodium acetate, distilling off most of the acetic acid and anhydride in the reaction product, cooling and filtering oft mono-acetyl compound, evaporating the remaining volatiles, and recrystallizing the residue first from aqueous alcohol and then from petrol.

Example 3 To 10 parts by weight of the detergent powder base of Example 1 was added 0.665 part of sodium percarbonate (containing 13% available oxygen) and 1.03 parts of N N-diacetyl-p-toluidine.

A 0.43% by weight aqueous solution of the total composition (containing 0.37% of the detergent powder base, 0.0032% by available oxygen and 0.038% of NzN-diacetyl-p-toluidine) was used to bleach a heavily tea-stained cotton sheeting using the procedure of Example 1. An increase in percent reflectance of 18.7 was observed, compared with 13.2 when a similar solution without amide was used.

Example 4 To 10 parts by weight of the detergent powder base of Example 1 was added 0.665 part of sodium percarbonate (containing 13% available oxygen) and 1.14 parts of N:N-diacetyl-p-chloroaniline.

A 0.43% by weight aqueous solution of the total composition (containing 0.37% of the detergent powder base, 0.0032% of available oxygen and 0.042% of NzN-diacetyl-p-chloroaniline) was used to bleach a heavily teastained cotton sheeting using the procedure of Example 1. An increase of percent reflectance of 16.9 was observed, compared with 13.2 when a similar solution Without amide was used.

Example 5 An aqueous bleaching solution was prepared incorporating 0.032% by weight of sodium perborate tetrahydrate (containing available oxygen), 0.12% of tetrasodium pyrophosphate and 0.046% of N:N-dibutyrylaniline (a liquid). Heavily tea-stained cotton sheeting was then washed with the solution using the procedure of Example 1. An increase in percent reflectance of 14.5 was observed, compared with 9.2 when a similar solution without the amide but containing the same amounts of perborate and pyrophosphate was used.

N:N-dibutyrylaniline can be prepared by the following procedure. Butyric acid and aniline are refluxed together in xylene solution for several hours with removal of the water eliminated by formation of monobutyrylaniline: the xylene is then evaporated ofl under reduced pressure and the cooled residue Washed successively with dilute hydrochloric acid and dilute caustic soda and recrystallized from benzene. The monobutyrylaniline, M.P. 8690 C. obtained is refluxed for several hours with butyric anhydride, and then distilled under reduced pressure, a fraction boiling at 184-7 C./ 17 mm. being collected. The solid monobutyryl compound impurity crystallizes on standing, and is filtered off, leaving NzN-dibutyrylaniline as a liquid.

Example 6 With 100 parts by weight of an aqueous solution containing 0.37 part of the detergent powder base of Example 1 and 0.023 part of sodium percarbonate (containing 14% of available oxygen) there was mixed 0.046 part of NzN-dibutyrylaniline. The detergent bleaching solution obtained was used to bleach a heavily tea-stained cotton sheeting using the procedure of Example 1. An increase in percent reflectance of 17.2 was observed, compared with 11.8 when the same solution but without the amide was used.

Example 7 A bleaching composition was prepared by mixing together 3.2 parts by weight of sodium perborate (containing 10% available oxygen), 12 parts of tetrasodium pyrophosphate and 3.2 parts of N-acetyl caprolactam. Heavily tea-stained cotton sheeting was then bleached using the procedure of Example 1 with a 0.18% aqueous solution of the composition. An increase in percent reflectance of 13.3 was observed, compared with 9.2 when a similar solution without the amide but containing the same amonuts of perborate and pyrophosphate was used.

Example 8 A bleaching composition was prepared and used exactly as in Example 7 except that 3.8 parts of N-acetylphthalimide was used as amide, and the solution contained 0.19% of the composition. An increase in percent reflectance of 11.5 was observed.

Example 9 To 10 parts by weight of the detergent powder base of Example 1 was added 0.62 parts of sodium percarbonate (containing 14% available oxygen) and 1.21 parts of N-acetyl saccharin.

A 0.44% by weight aqueous solution of the total composition (containing 0.37% of the detergent powder base, 0.0032% of available oxygen and 0.045% of N-acetyl saccharin) was used to bleach a heavily tea-stained cotton sheeting using the procedure of Example 1. An increase in percent reflectance of 17.1 was observed, compared with 11.5 when a similar solution without amide was used.

N:N'-diacetyl barbitone, a new compound referred to in this specification, can be prepared by the following procedure. Barbitone is dissolved in ethyl acetate containing a little concentrated sulphuric acid and ketene is passed into the solution until the required amount is absorbed. The reaction product is diluted with benzene and washed with dilute aqueous sodium carbonate until on acidifying the washings no solid appears. After washing with water and drying, the solution is evaporated and the N:N-diacetyl barbitone recrystallized from methanol, M.P. 127 C.

We claim: I

1. A process for bleaching materials which comprises contacting the material to be bleached with an aqueous solution containing eflective amounts of both hydrogen peroxide and a reactive acyl organoamide of the formula RCONR R where RC0 is a carboxylic acyl radical, R is an acyl radical, and R is an organic radical, said acyl organoamide having a titre in the Per-Acid Formation Test of not less than 1.5 ml. of 0.1 N Na S O from about A to about 4 molecules of amide being employed for each atom of available oxygen.

2. A process'according to claim 1 in which the aqueous solution is at a pH between 9 and 11.

3. A process according to claim 1 in which the amide is an acetyl organoamide.

4. A process according to claim 1 in which the amide is an acetyl organoamide in which the nitrogen of the amide group is substituted by a second acetyl radical.

5. A process according to claim 1 in which the amide is an NzN-diacylaniline.

6. A process according to claim 1 in which the amide is an NzN-diacetylaniline.

7. A process according to claim 1 in which the amide is N-acetyl saccharin.

8. A bleaching composition consisting essentially of an inorganic persalt and a reactive acyl organoamide of the formula RCONR R wherein RC0 is a carboxylic acyl radical, R is an acyl radical, and R is an organic radical, said acyl organoamide having a titre in the Per-Acid Formation Test of not less than 1.5 ml. of 0.1 N Na S O from about A to about 4 molecules of amide being employed for each atom of available oxygen.

9. A composition according to claim 8 and containing an alkaline material.

10. A composition according to claim 8 and containing an organic detergent.

11. A composition according to claim 8 in which the amide is an acetyl organoamide.

12. A composition according to claim 8 in which the amide is an acetyl organoamide in which the nitrogen of the amide group is substituted by a second acetyl radical.

13. A composition according to claim 8 in which the amide is an NzN-diacylaniline.

14. A composition according to claim 8 in which the amide is an NzN-diacetylaniline.

15. A composition according to claim 8 in which the amide is N-acetyl saccharin.

16. A bleaching composition consisting essentially of an inorganic persalt and a reactive diacyl organoamide of the formula RCONR R wherein RC0 is a carboxylic acyl radical, R is an acyl radical, and R is an acyl-free organic radical, said diacyl organoamide having a titre in the Per-Acid Formation Test of not less than 1.5 ml. of 0.1 N Na S O from about A to about 4 molecules of amide being employed for each atom of available oxygen.

17. A process for bleaching materials which comprises contacting the material to be bleached with an aqueous solution contain elfective amounts of both hydrogen peroxide and a reactive diacyl organoamide of the formula RCONR R wherein RC0 is a carboxylic acyl radical, R is an acyl radical, and R is an acyl-free organic 7 radical, said diacyl organoamide having a titre in the Per- Acid Formation Test of not less than 1.5 ml. of 0.1 N Na S O from about A to about 4 molecules of amide being employed for each atom of available oxygen.

18. A bleaching composition consisting essentially of an inorganic persalt and a reactive acyl organoamide selected from the group consisting of NzN-diacetylaniline, NzN-diacetyl-p-toluidine, N:N-diacetyl-p-chloroani1ine, NzN-dibutyrylaniline, dibenzanilide, N-acetyl caprolactam, N:N'-diacetylbarbitone, N-acetyl phthalimide, N-acetyl saccharin, N-acetyl anthranil, and NzN-diacetyl- 5:5-dimethylhydantoin, from about A to about 4 molecules of amide being employed for each atom of available oxygen.

19. A process for bleaching materials which comprises contacting the material to be bleached With an aqueous solution containing efiective amounts of both hydrogen peroxide and a reactive acyl organoamide selected from the group consisting of N:N-diacetylaniline, NzN-diacetyl-p-toluidine, NzN-diacetyl-p-chloroaniline, NzN-di- 8 butyrylaniline, dibenzanilide, N-acetyl caprolactam, N.N'-diacetylbarbitone, N-acetyl phthalimide, N-acetyl saccharin, N-acetyl anthranil, and NzN-diacetyl-SzS-dimethylhydantoin, from about A to about 4 molecules of amide being employed for each atom of available ovygen.

References Cited in the file of this patent UNITED STATES PATENTS 825,883 Heinrici July 10, 1906 2,576,205 Apperson Nov. 27, 1951 2,809,937 Gray Oct. 15, 1957 2,891,912 Schwartz June 23, 1959 2,898,181 Dithmar et al. Aug. 4, 1959 2,955,905 Davies et a1 Oct. 11, 1960 3,061,550 Baevsky Oct. 30, 1962 FOREIGN PATENTS 16,151 Great Britain of 1905 782,898 Great Britain Sept. 18, 1957 

1. A PROCESS FOR BLEACHING MATERIALS WHICH COMPRISES CONTACTING THE MATERIAL TO BE BLEACHED WITH AN QUEOUS SOLUTION CONTAINING EFFECTIVE AMOUNTS OF BOTH HYDROGEN PEROXIDE AND A REACTIVE ACYL ORGANOAMIDE OF THE FORMULA RCONR1R2, WHERE RCO IS A CARBOXYLIC ACYL RADICAL, R1 IS AN ACYL RADICAL, AND R2 IS AN ORGANIC RADICAL, SAID ACYL ORGANOAMIDE HAVING A TITRE IN THE PER-ACID FORMATION TEST OF NOT LESS THAN 1.5 ML. OF 0.1 N NA2S2O3, FROM ABOUT 1/4 TO ABOUT 4 MOLECULES OF AMIDE BEING EMPLOYED FOR EACH ATOM OF AVAILABLE OXYGEN.
 16. A BLEACHING COMPOSITION CONSISTING ESSENTIALLY OF AN INORGANIC PERSALT AND A REACTIVE DIACYL ORGANOAMIDE OF THE FORMULA RCONR1R2 WHEREIN RCO IS A CARBOXYLIC ACYL RADICAL, R1 IS AN ACYL RADICAL, AND R2 IS AN ACYL-FREE ORGANIC RADICAL, SAID DIACYL ORGANOAMIDE HAVING A TITRE IN THE PER-ACID FORMATION TEST OF NOT LESS THAN 1.5 ML. OF 0.1 N NA2S2O3, FROM ABOUT 1/4 TO ABOUT 4 MOLECULES OF AMIDE BEING EMPLOYED FOR EACH ATOM OF AVAILABLE OXYGEN. 